The Ground Water Supply of Southeastern Wisconsin (Will there be enough for the future?) Douglas Cherkauer Professor of Hydrogeology Department of Geosciences University of Wisconsin-Milwaukee
Topics to cover The water budget concept The confined aquifer has a deficit budget which cannot be sustained Alternatives: Continue with same operating procedure Try a new approach How can we achieve sustainability for the future?
The Water Budget (Conservation of Mass)
Continuity & Balance Water Budget: Inflows - Outflows = d(storage)/time Bank account: Deposits - Withdrawals = Change in Balance Source: USGS Sustainability requires continuing the balance
Recharge event When inflows < outflows, water level declines
Wasting System (spend all) Pumpage Losses Management options Recycling System (reinvest part) Discharge to sewers Losses Pumpage Pump = Losses + Discharge Net use ~ 100 gpdc To protect water quality, regulations tend to move us from recycling to wasting. For water quantity, this is counterproductive. Pump = Losses Infiltration (~80%) + Infiltration Net use = ~ 20 gpdc
Perspective on local ground water systems SE Wisconsin receives about 3 feet of precipitation per year, but only 2 to 6 inches becomes recharge. In recycling systems, this recharge can support a population density of 8 to 20 people per acre. In wasting systems, it can only support 2 to 5 people per acre.
Municipalities Unincorporated Waukesha Cedarburg Grafton West Bend Oconomowoc Brookfield/Elm Grove Mukwonago New Berlin Delafield/Hartland Menomonee Falls Pewaukee Germantown Thiensville Mequon Lisbon Richfield Vernon Cedarburg Grafton Jackson
Local Hydrogeology
General hydrogeology of southeast Wisconsin Unconfined aquifer 20 miles Maquoketa shale confining unit Resource assessment requires knowing recharge and inflows Confined sandstone aquifer Source: USGS 2200 feet
Shale
Representative water budgets
Wasting users Recycling Waukesha Cedarburg Grafton Brookfield/EG New Berlin Pewaukee Germantown Thiensville West Bend Oconomowoc Mequon Richfield
Deep GWD River Lake Recharge Lake Michigan Shale Transfers 100 gpdc from deep aquifer to rivers (from storage and diversion) Causes severe water level drops, migration of divide Not to scale Wasting/once-through of today
Groundwater levels in the sandstone aquifer 900 Unconfined 800 700 Dodge Head (feet) 600 500 Watertown # approximate western extent of Maquoketa # Washington Ozaukee Oconomowoc Pewaukee # Elm Grove # Milwaukee # Confined 400 300 200 Jefferson Waukesha Milwaukee Rock Walworth Racine Kenosha Watertown Oconomowoc Pewaukee Elm Grove Milwaukee 1860 1880 1900 1920 1940 1960 1980 2000 Year USGS (model results)
Summary of present status With wasting approach, ground water system can only support 2 to 5 people per acre. Confined aquifer is in deficit, so storage (budget balance) is drawn down and waste water transferred to Fox; cannot be sustained. Unconfined system has smaller balance, but more inflows. Susceptible to contamination, and use will impact lakes, wetlands, streams Individual communities face water shortages, but the ground water system is regional.
Does this mean that ground water cannot support current population and that we have to import Lake Michigan water?? ABSOLUTELY NOT!! The problem is NOT a shortage of water; there s lots. It IS our short-sighted consumption rather than management of the resource. We need to reinvest in our resource, not simply throw it away.
Possible solutions to deficit water budget in the deep aquifer Exploit another source (SOP; continued wasting) Lake Michigan Another aquifer (shallow system) Consider an alternative approach (managed utilization of water resources)
Deep GWD River Lake Recharge Lake Michigan Shale Reduces pumping of deep aquifer, but transfers effects of no management to Lake Michigan. Very likely a temporary fix Not to scale Alternative 1: Lake Michigan; wasting/no management
River Lake Shallow GWD Recharge Lake Michigan Shale Reduces pumping from deep aquifer, but transfers lack of management to shallow and surface water bodies. Streams and wetlands dry up; lakes lowered. Not to scale Alternative 2: Use shallow aquifer; wasting/no management
What s a viable solution Manage the total water resource (quantity and quality) Reduce demand (conserve) Blend shallow aquifer with deep Treat wastewater to highest standards Return to the same system (reduces loss to ground water system >80%) Effectively increases supply >5 times
River Lake Recharge Lake Michigan Shale Reduce use of deep aquifer, and blend with shallow Treat wastewater to high standards; return to system Manage balance between outflows and returns Not to scale Net loss from system drops from ~100 gpdc to <20 gpdc System with Regional Management and Recycling
Waukesha Cedarburg Grafton Brookfield/EG New Berlin Pewaukee Germantown Thiensville West Bend Oconomowoc Mequon Richfield
A sustainable alternative for Waukesha [Currently: Pump 9 mgd from confined aquifer; Fox R. flow is 2 mgd minimum and >13 mgd 90% of time.] If Waukesha reinvested half of their TWW (4.5 mgd) in infiltration beds to the shallow aquifer upstream from the city, the Fox flow would increase to 6.5 mgd minimum and >19 mgd Q90. Then install wells in shallow aquifer along the Fox, pump them (and perhaps treat the water). Use deep wells to augment (50:50) new wells in dry weather. Drops stress on confined aquifer by >50% and maintains minimum flow in Fox at today s levels.
It is already being done elsewhere Illinois communities (Elgin, Aurora) use Fox River as their water source. Richfield and many communities return wastewater to aquifer via private onsite treatment. Lake Geneva allows treated wastewater (TWW) to infiltrate its supply aquifer. Nationwide many communities recycle their TWW back into their supply source. It will not be easy, but it CAN be sustainable and environmentally friendly. It requires cooperation among users in a regional management plan.